1. Field of the Invention
The present invention relates to a plate material separating apparatus, and more specifically to an apparatus for separating only an uppermost plate material from stacked plate materials to feed only a single separated plate to a plate material processing machine such as turret punch press, for instance.
2. Description of the Related Art
In the conventional plate material separating apparatus, a plurality of vacuum pads are arranged on each of a plurality of vacuum hangers fixedly arranged at regular intervals on both sides of the horizontal beam, in such a way as to extend in the vertical direction; and after a plate has been sucked by the vacuum pads, the vacuum hangers are lifted vertically to separate the sucked uppermost plate from the stacked plates.
Further, Japanese Published Unexamined (Kokai) Utility Model Application No. 3-23132 discloses a vibration type plate material separating apparatus as follows: a stretch member movable up and down by a hydraulic cylinder is provided; a plurality of suction pads are attached to the ends of shafts attached to the stretch member, respectively; and a vibration mechanism is provided for each suction pad to separate the sucked plate from the stacked plates, whenever two or more plates are sucked simultaneously.
In the prior art plate material separating apparatus as described above, however, although the plate can be lifted and thereby separated from the stacked plates by use of the vacuum pads arranged on the vacuum hanger, when the uppermost plate sticks to the second plate, it is impossible to separate the uppermost plate from the stacked plates. Further, if the vacuum pads attached to the ends of the shafts are vibrated or oscillated, when the sticking force between the two adjacent plates is strong, there exists a case where it is impossible to separate no plate from the stacked plates. Further, when two plates are lifted together, there exists a case where the upper plate cannot be separated from the second plate even if vibrated.